There has been a need for a sturdy, portable apparatus that can be used by employees of water companies to check for leaks in residential and commercial plumbing systems, particularly flush toilets. The instant device fills this need as it consists of a minimum number of parts and does not contain a diaphragm. The device can be used to detect leaks in household toilets of a tank type or even toilets using Sloan valves to control the flow of water into the bowl. The prior art devices of this type utilize diaphragms as part of their structure. U.S. Pat. No. 2,755,880 to Hofmann discloses an acoustic device in which vibrations of a diaphragm caused by vibrations in a water pipe are transmitted through a tube to ear pieces. U.S. Pat. No. 2,389,868 to Olson discloses an acoustic stethoscope that not only utilizes a diaphragm but also relies on an electric circuit. U.S. Pat. No. 2,261,375 to Jacobs discloses an apparatus for determining the characteristics of a lake bed or the like in which a line connects a metal device, designed to sink to the bottom of the lake, with an acoustical diaphragm that is connected to means for transmitting sound vibrations to earphones. U.S. Pat. No. 3,458,656 to Sewerin discloses an apparatus for localizing water leakage that utilizes a geophone and an electric circuit.